I did that and it is reported as bug #1835033.
When I killed the frozen gnome-shell process, it had recovered by the time I switched back to it and I was then able to close the offending window.
I did that and it is reported as bug #1835033.
When I killed the frozen gnome-shell process, it had recovered by the time I switched back to it and I was then able to close the offending window.